Such nozzles are used in injection molding equipment to feed a fluid processing material at a predetermined temperature and under high pressure to a separable mold block respectively, to a mold insert. Most such nozzles comprise a tubular casing in the form of a feed pipe fitted with a flow duct for said fluid processing material and with a nozzle tip which is inserted terminally into said pipe and which subtends the discharge aperture of said flow duct.
The state of the art contains the most diverse kinds of injection molding nozzles, in particular those used for edge gating. Most of these nozzles comprise a casing subtending at least one fluid processing material flow duct and at least one nozzle tip running perpendicularly to the longitudinal nozzle casing axis.
Such an injection molding nozzle illustratively is known from the German patent document DE 196 18 960 A1. It comprises several nozzle tips which may be screwed laterally into the externally heated nozzle casing and which, once screwed-in, run radially outward perpendicularly to the nozzle casing's longitudinal axis. The nozzle casing is fitted with a positioning flange segment received in an aperture subtended in the mold insert. The nozzle casing is positioned transversely by means of said segment, and on the other hand it may be advanced longitudinally to allow screwing-in the nozzle tips. Then said casing is moved back into an assembled position wherein it is longitudinally positioned by the nozzle tips received in the mold insert. As a result the nozzle casing is configured longitudinally in the same plane as contains the gates constituted in the mold insert. The nozzle tips and the mold are sealed from each other by seals that are provided at the nozzle tips and at the mold insert and that cooperate radially relatively to the nozzle tips.
One drawback of the injection molding nozzles disclosed in DE 196 18 960 A1 is the relatively high cost of affixing the nozzles—they can be installed into the mold only from below. Accordingly the mold must be disassemblable, entailing not only mold cost but also time delays.
The nozzle tips moreover should be made of a thermally highly conducting substance to assure optimal temperature crossover between the nozzle casing and the nozzle tips to always keep the fluid processing material at an optimal temperature as far as the gate. On the other hand the nozzle tips' sealing faces in contact with the mold should be made of a substance of low thermal conductivity to minimize the heat transfer between the nozzle tips and said mold.
In the design of the injection molding nozzle of DE 196 18 960 A1, the nozzle tips and their sealing faces are integral, namely they are made of one and the same substance. This feature however precludes the herein desired objective of combining optimal injection temperature of the fluid processing material and low heat transfer between said nozzle tip sealing faces and mold. Said known injection molding nozzle incurs a further drawback in that the nozzle casing's flow duct and the nozzle tip boreholes continuing said flow duct as far as the injection site are substantially orthogonal to each other, entailing high flow impedance and commensurately adversely affecting injection molding.